An information search system is a system that is able to provide information search service to a user. An example is a commonly used search engine in the Internet. Given the usage in the Internet, search engines have become one of the indispensable tools for users to surf the web. From a user's perspective, a search engine normally provides a web page that includes a search box. The user inputs in the search box a keyword or other search criterion, which is subsequently submitted to the search engine by an associated browser. Thereafter, the search engine returns information that matches the keyword inputted by the user.
Given a user search request (e.g., a search keyword inputted by the user), the search engine is generally able to find a number of relevant pieces of information with the number probably reaching from several tens to several tens of thousands. From the user's perspective, only the information placed in relatively high ranks in the search result will the user pay attention to. Therefore, how to rank these pieces of information has become particularly crucial when the search engine provides a search result to the user. Whether or not the ranking of the search result is reasonable will have a direct impact on the user experience.
When the search engine ranks information, a variety of factors are taken into consideration. The factors that are considered may include, for example, sources of the information, reliabilities of the information, user response, and so forth. Among these factors, user response is a key factor that affects ranking of the search result. For instance, when a search keyword is “China Central Television”, eighty percent of users click an official home page of the China Central Television. If user response is the only factor considered, the search engine may reasonably place the official web page of China Central Television at the top of a search result that corresponds to the keyword “China Central Television”.
In order to achieve the aforementioned result, existing search engine counts the amount of user response associated with various pieces of information that match a search keyword, and generates search result for a user in a descending order based on the amount of user response. According to studies on existing technologies, the inventors have observed the following problems of the existing method for generating search result. For newly published information, an initial value for the amount of responses may be zero (or very low) that results in a low rank. Because of the low rank, newly published information can hardly be noticed by the user. Consequently, the ranking can hardly be improved. From another perspective, some user may quickly change the amount of responses through certain cheating practices (such as fraud clicks) to cause his/her published information to be placed in a higher rank within a search result, and thus affect normal benefits of other users. Therefore, from a user's point of view, search results that are generated by existing technologies have shortcomings that impact user experience.